Natural gas (i.e., methane (CH4)) is considered one of the cleanest, safest, and most useful of energy sources. When burned, it produces a great deal of energy with fewer emissions than many other energy sources, and therefore it has many uses in residential, commercial, and industrial applications. One reason that natural gas is considered safe is its narrow combustion limits, which ensures predictability in use. Natural gas will only ignite when air contains between five and fifteen percent natural gas. Due to its combustible nature, however, there is still a risk of explosion when using natural gas, which makes it very important to quickly determine where gas leaks may be occurring. Other gases have similar properties and risks. There are some gas detection sensors currently available and/or currently being developed. However, these sensors are either high in power consumption, high in cost, or both. Widespread application of such sensors (e.g., one or more at every home, business, etc.) could be quite costly, and in some applications (e.g., for use with gas utility meters, which typically run on battery power) may not even be feasible.
In the drawings, the leftmost digit(s) of a reference number may identify the drawing in which the reference number first appears.